I've actually thought that Twitter could make quite the business model out of using their search acquisition and some other things to work with brands to track trends. The recent piece on O'Reilly blog post (http://broadcast.oreilly.com/2008/11/why-jerry-seinfeld-prob...) about tracking the emotional connection to the MS Seinfeld ad is exactly what I'm thinking.

Add to that some permission marketing stuff and they could be onto a goldmine...